Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with transitional graphical user interface showing my new design in a first state;

FIG. 2 is a front view thereof in a second state; and,

FIG. 3 is a front view thereof in a third state.

The outermost broken lines in the figures show a display screen and form no part of the claimed design. The broken lines depict portions of the graphical user interface and form no part of the claimed design.

The appearance of the transitional graphical user interface sequentially transitions between the images shown in FIGS. 1-3. The process or period in which one image transitions to another forms no part of the claimed design. 

CLAIM I claim the ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 